NSA leaker Edward Snowden is the subject of an open letter of support just published from behind bars by John Kiriakou, a former CIA agent currently serving time for sharing state secrets.

In a letter dated June 13 and published Tuesday by Firedoglake, the imprisoned CIA vet salutes Snowden for his recent disclosures of classified documents detailing some of the vast surveillance programs operated by the United States’ National Security Agency.

“Thank you for your revelations of government wrongdoing over the past week,” Kiriakou writes. “You have done the country a great public service.”